Smart phones are increasingly popular with the development of smart terminal technology. When a user makes a call through the smart phone, his face may often touch a screen of the smart phone. In this case, when a call hang-up key or a speaker key in the screen is touched mistakenly, some unnecessary interference may be cased.
In order to prevent the above interference, the smart phone is generally provided with a proximity sensor inside by a phone provider to determine a status of the smart phone. The proximity sensor transmits an infrared light pulse outwards and determines whether an object is in proximity based on an amount of energy of the infrared light received by an infrared photosensitive diode. Furthermore, in order to improve a transmittance of the infrared light pulse, it requires arranging a hole in a non-displaying region of the smart phone, thereby causing a low screen-to-body ratio of the smart phone.